Product number: 7500

Presence-Absence Broth is used for the detection of coliform bacteria in water treatment plants or distribution systems using the presence-absence coliform test in a laboratory setting. Presence-Absence Broth is not intended for use in the diagnosis of disease or other conditions in humans.

The Presence-Absence (P-A) test is a presumptive detection for coliforms in water. The test is a simple modification of the multiple-tube procedure. One 100 mL test sample is inoculated into a single culture bottle to obtain qualitative information on the presence or absence of coliforms, through the presence or absence of lactose fermentation. This test is based on the principle that coliforms and other pollution indicator organisms should not be present in a 100 mL water sample.

Comparative studies with the membrane filter procedure indicate the P-A test may maximize coliform detection in samples containing many organisms that could overgrow coliform colonies and cause problems in detection. The P-A test is described in standard methods for water testing and U.S. EPA.


Formula Liter
Beef Extract 3 g
Enzymatic Digest of Gelatin 5 g
Lactose 7.46 g
Enzymatic Digest of Casein 9.83 g
Dipotassium Phosphate 1.35 g
Monopotassium Phosphate 1.35 g
Sodium Chloride 2.46 g
Sodium Lauryl Sulfate 0.05 g
Bromcresol Purple 0.0085 g

Final pH: 6.8 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.


  1. Prepare triple strength concentration by adding 91.5 g of the medium in one liter of purified water.
  2. Mix thoroughly.
  3. Dispense 50 mL into a 250 mL screw-cap milk dilution bottle.
  4. Autoclave at 121°C for 12 minutes.
  5. Cool and add 100 mL water sample.

Order Details

Product # Product Description
7500A Presence-Absence Broth, 500 g
7500T Presence-Absence Broth, 5 kg
7500C Presence-Absence Broth, 10 kg

Reference Material

7500 - Presence-Absence Broth, Product Information Sheet [English] [Portuguese]
7500 - Presence-Absence Broth, Safety Data Sheet [Danish] [Dutch] [English] [EU English] [Finnish] [French] [German] [Hungarian] [Italian] [Spanish, Mexico] [Swedish]

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